Extreme and unpredictable weather seen around the world in 2019 will get worse as ice sheets in Greenland and Antarctica continue to melt, according to an international research collaboration published in Nature today – and global government policy needs urgent review to prevent dangerous consequences.

The collaboration led by Associate Professor Nick Golledge from Victoria University of Wellington’s Antarctic Research Centre and involving scientists at GNS Science and from Canada, the UK, Germany and the USA used climate models to simulate what might happen when water from melting ice sheets enters Earth’s oceans.

Last week it was colder in Chicago than at the North Pole, while wildfires raged in Australia as temperatures in Adelaide hit 47 degrees.

Despite the cold snap in the US, overall temperatures are warming and under current policy settings, the Earth’s temperature will increase by 3 to 4 degrees by 2100.

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Our new experiments show if we drastically reduce emissions we can limit future impacts

Dr Liz Keller

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“With this level of warming, a significant amount of melt water from the Greenland and Antarctic Ice Sheets will enter Earth’s oceans,” Associate Professor Golledge says.

“According to our models, this melt water will cause significant disruption to ocean currents and change climate around the world.”

The model predictions of Associate Professor Golledge and his colleagues show that in some areas of the world, these ocean changes will lead to more extreme weather events and greater year-to-year variation in temperatures.

The study also found that in the north Atlantic Ocean the influx of melt water will lead to significant weakening of deep Atlantic circulation, which affects coastal ocean currents such as the Gulf Stream.

This will lead to warmer air temperatures in Central America, Eastern Canada, and the high Arctic, but reduced warming over north-western Europe on the other side of the Atlantic.

“We will start to see more of this recent extreme weather, both hot and cold – with incredibly disruptive effects for agriculture, infrastructure and human life itself.

“This is not currently accounted for in current global climate policies.

“New Zealand is making a great effort, with the Zero Carbon Bill and attempts to find a cross-party solution – but globally, policy is lagging far behind the science.”

The ice sheet effect on rising sea level was also calculated in the study.

“Our new experiments show if we drastically reduce emissions we can limit future impacts.”

Developments in research methods have led this paper and another published in the same issue of Nature to conclude sea level rise by 2100 may be significantly less than was predicted in a high-profile 2016 study, Associate Professor Golledge says.

Dr. Tamsin Edwards, a researcher from King’s College London and lead author of the second study said, “The close agreement between the two new studies is really encouraging – it highlights how much progress is being made in this area”.